1. Field of the Invention
This invention relates to a bobbin for use in a sewing machine and more particularly to a novel and highly effective bobbin the use of which ensures that the sewing machine is always properly lubricated.
2. Description of the Prior Art
Sewing machines have been known for more than a century. Properly maintained, a sewing machine will last for many years. A major part of the maintenance of a sewing machine involves periodic lubrication with a good-quality sewing machine oil. Overlubrication, however, is unnecessary and even harmful, since an excess of oil may attract airborne dust, which is ubiquitous in an indoor environment, especially when fabrics are being processed and otherwise handled. Overlubricated parts may eventually become sticky or gummy.
Sewing machines intended for industry, for example for use in making seat covers for cars, are normally given heavy usage. Because of heavy production schedules, there is a tendency for a user of an industrial sewing machine to meet output quotas and deadlines even at the cost of neglecting the prescribed oiling of the machine.
Sewing machines intended for the home tend to be put to much lighter use. The prescribed oilings of a home-type sewing machine are normally at such infrequent intervals that a user of the sewing machine can easily forget to apply oil at a scheduled interval and moreover may lose track of the last time oil was applied.
The frequency of oiling of any sewing machine, whether intended for industrial use or home use, should be commensurate with the amount of work done by the machine. That is, the heavier the usage of the sewing machine the more frequently it should be lubricated. Often a person responsible for oiling a sewing machine will not recall clearly or know in the first instance the usage to which the machine has been subjected, particularly if more than one person has used the machine. The machine may be oiled excessively if each of several users assumes the responsibility of applying oil or insufficiently if each user assumes that the oiling has been done by another user.
Various expedients may be employed by users of sewing machines in order to establish a proper oiling schedule. For example, every time a machine is oiled, the person adding the oil may apply a gummed label to the machine indicating the date (if a home-type machine) or the date and time of day or work shift (if an industrial-type machine) of the oiling. Most users, however, are not sufficiently disciplined to do this on a regular basis, and if a gummed label is applied, users of the machine are likely to become accustomed to its presence and fail to pay much attention to it. Moreover, the time of oiling is not the sole criterion for determining when the next oiling is due; the frequency of use of the machine should also be taken into account, and of course a gummed label applied to the machine and bearing only the time of last oiling does not supply this information.
It might be thought that a sort of clock similar to those used to record engine time on an aircraft or a sort of odometer similar to those used to record mileage on cars and trucks should be incorporated in a sewing machine to provide information regarding the usage of the sewing machine so that a user of the sewing machine can determine when oiling is required, much as a user of an airplane, car or truck can determine when a change of oil is necessary by referring to the engine clock or odometer. However, airplanes, cars and trucks are relatively expensive, so that the incorporation of relatively expensive instrumentation is warranted. A sewing machine is much less expensive, and the incorporation of expensive instrumentation to determine the frequency of oiling is much more difficult to justify.
It is believed that no ideal solution to the problems discussed above is found in the prior art.